As trade tensions between the world’s largest economies continue to escalate, the US has warned China not to weaken its currency as an alternative to tariffs.

“As we look at trade issues there is no question that we want to make sure China is not doing competitive devaluations,”Treasury Secretary Steve Mnuchin told the Financial Times in an interview published Wednesday. “We are going to absolutely want to make sure that as part of any trade understanding we come to that currency has to be part of that.”

On the campaign trail, Trump had repeatedly vowed to label China a currency manipulator. But the US Treasury has declined to do so several times this year in semiannual reports on the foreign exchange policies of major trading partners.